The modern diesel engine starts with a block, containing all the parts for the basic internal combustion process. There is an open space in the block for each cylinder, where the combustion process takes place.

Crankshaft

The first piece we need is the crankshaft. This is the piece that converts the linear motion created by combustion into rotational motion.

Connecting Rods

Next we need something to connect the crankshaft to the cylinder and carry the force of the combustion to it. These are the connecting rods.

Pistons

Each connecting rod attaches to a piston at the top. The pistons create the bottom of the combustion chamber and move up and down in the cylinder during operation.

Cylinder Head

At the top of the block is the cylinder head. This closes the top of the combustion cylinder to contain the force of the combustion event. The head can be one unit covering all the cylinders or multiples with each covering a portion of the cylinders, depending on the design.

Valves

Now that the cylinder is closed off, the engine needs valves to allow the combustion gases to flow out and fresh air to flow in during the process. There are usually two valves for exhaust and two for intake air on each cylinder.